In fact, it is by training with them that, a fatal day that you get confronted by a real and not totally incompetent challenger in a street situation, you will discover only at that very same moment and for the first time that all you have learnt won't work at all - and you will get killed.

So, complacent ukes are very useful if you're so naive and daring to think of using aikido for self-defense purposes (you should know that a martial art is not meant for that... come on everybody knows that... you should rather cultivate aiki instead, for aiki-do is not for self defense but to enhance your spiritual side...) - complacent ukes are quite useful if you're planning... suicide.